1. Field of the Invention
This invention relates generally to flexible shaft couplings having meshing gear teeth and more particularly to a symetrical sealed gear coupling which can be easily disassembled for maintenance of the coupling or equipment connected by the coupling.
2. Description of the Prior Art
Flexible gear type couplings are widely accepted for use in transmitting high torques between substantially aligned driving and driven shafts. Such couplings have been modified in many ways to meet the requirements of particular applications. For example, flexible gear couplings are often used to transmit power from electric motors to gear boxes or other types of drive trains. The operating environment usually dictates the characteristics of the particular coupling to be used such as, the type and frequency of lubrication, the type of shaft mounting, the type of lubricant seals, and the manner of disassembly for maintenance.
One particularly vexing application has developed with respect to couplings suitable for transmitting power in rapid transit vehicles, especially rapid transit trains or individually propelled train cars. Such vehicles require considerable power, are subject to cyclic loading because of frequent starts and stops, and must be reliable since a unit failure can slow down the whole system.
It is especially important that necessary maintenance be easily and quickly accomplished. It should be understood that it is often necessary to repair or replace the electric drive motors or transit vehicles; to do so requires that the motor be quickly and easily disconnected from the drive system. To achieve an overall low maintenance time, the spare parts are usually stocked, including motors and couplings.
More particularly, when a faulty motor is to be repaired or replaced, it is disconnected from the drive train and a new or repaired motor installed in its place to permit the vehicle to be immediately returned to service. To disconnect the motor, it must be disconnected from the coupling connecting it to the drive train. Because of the drive loads involved, the coupling may be connected by a press fit on a tapered shaft of the motor; therefore, it may be necessary to remove the coupling by hydraulic pressure. This is not easily accomplished if a non-separable coupling is used since the motor (or coupling and associated drive train) would have to move axially simultaneously upon disengagement. Therefore, a separable coupling is preferably used so that the motor may be backed away, carrying half of the coupling with it; thereafter, the coupling half may be removed from the motor shaft.
It should also be understood that a motor that is removed may remain in storage pending repair; likewise, once repaired, it may remain in storage until needed. Similarly, a new motor may be readied for use by installing a half-coupling on its output shaft. In addition, several couplings may themselves be stored as spares, either new or reconditioned. A new or reconditioned coupling should be packed with grease or oil to prepare it for use; unfortunately, this often cannot be done since the couplings are not provided with seals to retain the lubricant in their separated half-coupling condition; if the halves are stored on end to retain the lubricant, the lubricant usually becomes contaminated by dust or other debris in the storage environment. An example of a separable coupling which does not include seals for each half is shown in U.S. Pat. No. 3,871,191.
Accordingly, an object of this invention generally is to provide a gear type flexible shaft coupling especially suitable for the transmission of power between a driving machine, such as an electric motor, and a driven machine, such as a drive train gearbox. More particularly, an object is to provide, in combination, a gear coupling which is easily separable into individual sealed coupling halves; to provide symetrical coupling halves so that either half may be used as the driving or driven member; to provide a means for radially aligning the coupling halves when they are connected to each other; to provide an easily removable, preferably disposable, inner seal to readily expose the shaft end for removal of the coupling half; to provide a substantially uniformly distributed lubricant reservoir; and to provide simple means for hydraulically removing the coupling halves from their associated shafts.